1. Technical Field
The present disclosure relates to a common mode filter, and relates, in particular, to improve removal capability of the common mode noise, impedance matching and so on with acquiring a de-emphasis function in a common mode filter having an inductor, a capacitor and a resistor.
2. Description of the Related Art
In recent years, high-speed serial interfaces such as HDMI (High Definition Multi-media Interface) and USB (Universal Serial Bus) have been widely popularized in accordance with increases in data amount. The high-speed serial interfaces adopt differential transmission technologies from the viewpoint of speedup, high noise immunity and noise reduction, and common mode filters are widely used as noise suppression parts in order to further promote high noise immunity and noise reduction when the interfaces are incorporated into set systems and the like.
As the features of common mode filters, there can be enumerated differential transmission characteristics (giving no influence on differential transmission waveforms) of which the high-frequency characteristics for speedup are improved, and impedance matching characteristics matched to differential transmission lines based on common mode noise removal capabilities.
Conventionally, a common mode filter configuration having a terminator circuit as shown in a Patent Document 1 of Japanese patent laid-open publication No. JP 2010-27951 A is proposed as a technology to improve the common mode noise removal capabilities of common mode filters.